Draw the opening and locating reference
Sketch the two limits that define the available cross-grain space. Label the actual measured opening and the point or line used to locate the part. The calculator treats the opening as fixed while the modeled wood changes width. If the surrounding construction also moves, deflects or changes with temperature, review that behavior separately; the opening arithmetic does not model it. State whether the entered width belongs to the final finished part or to stock still awaiting machining. A finish or trim detail that changes the envelope must be resolved in the drawing before using the comparison.
Keep the total reserve separate from the present gap
Current gap is opening minus measured width. Wet-endpoint gap is opening minus predicted wet width. Required reserve is your separately entered total space that must remain after the wet endpoint, for reasons defined by the actual construction. The planner subtracts that reserve to show an arithmetic balance. It does not supply a recommended clearance. A positive balance says the entered numbers leave that space; it does not certify the measurement, part geometry or joint. A negative balance identifies an input scenario that cannot retain the reserve in the fixed opening.
Read current expansion and seasonal swing differently
Expansion from now describes the change from the current MC to the wet endpoint. Seasonal swing covers the entire entered dry-to-wet interval. Those values are equal only when the current reading is at the dry endpoint. For the tabletop example, expansion from now is 9.024 mm while seasonal swing is 13.536 mm. Do not substitute the larger seasonal value as a present-direction travel without considering where the part starts. Conversely, do not plan a detail around the current expansion alone if it must accommodate the full service cycle.
Use the locating reference to explain edge displacement
Under the simple centered-reference scenario, half of each modeled width change appears at each side. Under the one-edge-reference scenario, the opposite side takes the full modeled width change. These statements are drawing assumptions used to describe free displacement, not instructions for fixing a tabletop. They require the actual detail to permit the intended movement. The control does not analyze several attachment points, asymmetric constraints or joint forces. Confirm which reference the construction uses and whether the dry and wet travel can occur without hitting a stop.
Obtain the actual attachment geometry
Review the chosen hardware instructions and the drawing for the exact attachment being used. A displayed displacement is not a slot length: fastener diameter, head or washer support, slot location, usable travel in both directions, edge distances and installation position require their own specified detail. Do not machine a slot solely by copying the calculator output. Test the planned arrangement on appropriate project material and document what was checked. If the hardware instructions and the intended movement disagree, resolve the attachment design rather than changing the moisture inputs to make the result smaller.
Carry both endpoints through the fit review
Check what remains engaged at the dry endpoint as well as what collides at the wet endpoint. A panel might avoid a wet-end collision while a dry-end detail still fails its intended function. This planner displays dry width and edge travel, but it does not calculate groove engagement, joint strength or minimum retention. Keep those dimensions and criteria on the drawing. If the construction uses a moving surround, mixed materials or a restrained panel, a separate construction-specific review is necessary. The simple fixed-opening comparison can still be kept as one clearly labeled piece of evidence.
Export the review with its unresolved items
Add the opening reference, reserve rationale, attachment document and drawing revision to the notes. Use CSV for a numerical review and JSON for an editable project backup; the print view includes the current form and results. Keep any unresolved detail in the record so the next person does not read “reserve available” as approval to manufacture. After installation or a later inspection, compare physical observations with the preserved estimate and note what changed. The calculator provides a traceable planning scenario, while the actual construction review determines the next operation.
Sources and method boundary
USDA Wood Handbook, Chapter 13 (2021) — The planner uses the free dimensional-change approximation. The opening, reserve and locating-reference arithmetic are WoodCutTool drawing scenarios added around that model. Checked 2026-10-11.